Microelectromechanical system devices (MEMS) may be manufactured from thin film processes. These processes may involve a series of thin films deposited in layers, the layers being patterned and etched to form the devices. In order to allow the devices to move, one layer may be an isolation layer. An isolation layer is one that is used in forming the layers of the device acting as a structural member, but that may be removed when the device is complete.
Removal of the isolation layers may involve an etching process, using a material as the etchant that only acts on the sacrificial layer material. In some cases, the isolation layer may be an oxide that may be removed with a dry gas etch. Other forms of isolation layers are also possible, as are other methods of removal. The removal of the isolation layer typically results in a gap, through which a member of the device will move upon actuation.
MEMS devices often actuate through the use of electrical signals that cause a voltage differential between a first conductive layer and a second conductive layer separated by the gap. During dry, gas etching of the isolation layer, an electrostatic charge may build up on the layers, causing the movable member to become attracted to the other conductive layer. In extreme cases, the two layers may become stuck together and the device becomes inoperative. In less extreme cases, the movable element may become damaged or deformed and subsequently not operate correctly.